Regenerative Medicine is a relatively young interdisciplinary science intended to the ex vivo manufacture of 3D proto-tissues able to replace injured organs and solid tissues requiring the strict cooperation of material scientists, who should fabricate biocompatible scaffolds with a wide range of physical parameters, biochemists and molecular biologists, who should produce highly purified, bioactive molecules in large quantities and cell biologists, who should provide the appropriate cells.
Adult STEM cells, and in particular mesenchymal stem cells, are so far the best cell type for this purpose, because of their properties of self-renewal and multipotency. They were originally isolated from bone marrow; more recently subcutaneous adipose tissue was also shown to contain adult stem cells in its stromal component and it is receiving more and more attention due to the simple surgical procedure, the easy and repeatable access, the easy enzyme-based isolation procedures and the relative large available quantities.
Adipose-derived Stem Cells (ADS) display morphological, immune phenotypic, colony frequency, and differentiation capacity similar to those of the longer-time characterized mesenchymal stem cells isolated from bone marrow. As an example, they can be easily induced to differentiate towards osteoblasts, adipocytes, chondrocytes.
In regenerative medicine applied to the ex vivo generation of solid tissues, the microenvironment where cells are inserted plays an essential role contributing physical—e.g. mechanical, topographical, electric-cues, as well as chemical signals—e.g. growth or differentiation/factors, adhesion molecules.
The great efforts to develop new materials and innovative cell culture systems are often hampered by the relatively limited in vitro growth of the cells, since in these complex systems primary cells are generally used, which inevitably undergo senescence within few passages.
Fresh primary stem cells must thus be continuously isolated, which is time-consuming and requires killing of animals.
Therefore, the establishment of a cell line with features of stem/progenitor cells may help to overcome the limitations identified above. Moreover, continuous cell lines may provide a more homogeneous and reproducible reagent for cell cultures.